Former large monitoring base of US intelligence organization NSA in Bad Aibling Thomson Reuters A leaked NSA newsletter published Wednesday highlights the collection of phone metadata as one of the agency's "most useful tools."

The document — which was leaked by Edward Snowden and published by The Intercept — says that the NSA has used metadata such as numbers called, IP addresses, and call duration to yield "concrete results," such as the capture of terror suspects Khalid Sheikh Mohammed and Abu Zubaida.

It's worth noting that while the collection of specific metadata may have helped catch terror suspects, the agency's bulk collection has a far worse record.

That program forced American telephone companies to hand over metadata on all of their customers to the NSA, which included phone numbers and duration of calls, but not content. It was changed in late 2015 to keep bulk records with the companies, requiring a court order to look at specific records.

Snowden leaks largely corroborated a 2006 story on the program from USA Today, which stated that the NSA's goal was "to create a database of every call ever made" within the nation's borders, according to an unnamed official.

An independent review board found that the bulk collection program, dubbed Section 215, showed "minimal value in safeguarding the nation from terrorism. ... we have not identified a single instance involving a threat to the United States in which the program made a concrete difference in the outcome of a counterterrorism investigation."

At the time of the document's internal publication in January 2004, it said its FASCIA II database of metadata records held more than 85 billion records, with about 125 million records added each day. That number was expected to increase to 205 million records per day, the document said.

The document is an interesting find in the Snowden cache, especially considering some of the picks for the incoming Trump administration. Both the nominee for Attorney General and CIA Director have advocated for the increased domestic spying that was implemented under President George W. Bush after 9/11.

"Congress should pass a law re-establishing collection of all metadata, and combining it with publicly available financial and lifestyle information into a comprehensive, searchable database," Kansas Rep. Mike Pompeo, who was tapped for Director of CIA, wrote with coauthor David Rivkin, Jr. in a Wall Street Journal editorial in January. "Legal and bureaucratic impediments to surveillance should be removed."

You can read the full document below, or read others in the cache at The Intercept.